Semiconductor wafers, substrates, magnetic disks, optical disks, flat panel display components and the like are examples of wafers which are often prepared using a sequence of chemical or photochemical processing steps. These processing steps are frequently performed while the wafer is moving, particularly rotating. Rotating or spinning a wafer during processing promotes uniform application of chemicals, whether such chemicals are applied in liquid or gaseous form, and accelerates drying of the wafer. Spinning is also useful in the application of heated gases for even drying. Accordingly, wafer processing heads have been designed to grasp a wafer along peripheral edges and to spin it about a central axis.
One type of wafer holder utilizes one or more gripping fingers which are deflected into relatively spaced or open positions. The wafer is then loaded by positioning it between the fingers. The deflected fingers are then contracted inwardly to engage the wafer along the periphery.
The wafer gripping fingers can be mounted in a rotor plate of a processing head, or other support member, using a laterally extending mounting flange connected to the core of the finger. The flange connection is advantageously by a diaphragm structure having a relatively thin annular web or septum which provides the flexibility which allows deflection of the finger by an actuating mechanism. Operation of the fingers can lead to weakening of the septum. This can cause positioning changes and erratic finger positioning over time. Such erratic positioning is problematic generally and particularly in automated wafer handling systems which feed and remove the wafers from the processor using robotic arms or other mechanisms which rely upon precise positioning. Failures of the wafer gripping fingers have also been experienced in part due to axial loading of the thin septa of the wafer finger mounting flanges. This causes equipment shutdowns and lost production time.
Accordingly, there is a need in the art for an improved wafer processor having a wafer holding and support construction which includes angularly displaceable wafer engagement fingers which have improved life and positional reliability.